1. Field of the Invention
The present invention relates to a golf ball which makes it possible to obtain a soft hitting feeling and a sufficient carry. In particular, the present invention relates to a golf ball comprising a cover composed of a base material containing an ionomer resin, which provides a soft hitting feeling, which is satisfactory in resilience to obtain a sufficient carry, and which hardly tends to suffer scratches on its cover surface.
2. Description of the Related Art
Ionomer resins of metal salt of ethylene-(meth)acrylic acid copolymer have been hitherto widely used as a material for a cover of a golf ball because they are advantageous and excellent in resilience and durability. However, the golf ball based on the use of such an ionomer resin as a material for its cover has a hard hitting feeling. Therefore, it has been tried to improve this drawback.
In order to soften the cover and obtain a soft hitting feeling, for example, it has been suggested to use, as a material for a cover, a mixture of an ionomer resin of sodium salt or zinc salt of ethylene-(meth)acrylic acid copolymer and a soft ionomer resin of sodium salt or zinc salt of ethylene-(meth)acrylic acid ester-(meth)acrylic acid terpolymer (see U.S. Pat. Nos. 4,884,814 and 5,120,791).
Such a suggested golf ball has a soft hitting feeling, however, it tends to undergo decrease in resilience of the cover and provide an inferior carry, as a result of its softened cover.
In order to soften the cover while maintaining the resilience of the cover, it has been suggested to use, as a material for a cover, a mixture of an ionomer resin of metal salt of ethylene-(meth)acrylic acid copolymer and a partially saponified resin of ethylene-unsaturated carboxylic acid ester copolymer (see Japanese Laid-Open Patent Publication Nos. 5-345051 and 6-313075). However, compatibility is not sufficient between the ionomer resin of metal salt of ethylene-(meth)acrylic acid copolymer and the partially saponified resin of ethylene-unsaturated carboxylic acid ester copolymer. For this reason, when the partially saponified resin of ethylene-unsaturated carboxylic acid ester copolymer is mixed in an excessive ratio, a problem arises in that the cover surface tends to suffer scratches when such a golf ball is hit with a golf club.